Integrated Optical Circuits

A detailed study has been made of electroabsorption avalanche photodiodes (EAP) fabricated in high-purity n-type epitaxial GaAs, and the attenuation of high-purity planar GaAs waveguides has been examined at wavelengths close to the absorption edge. The results open up the attractive possibility of forming in high-purity GaAs waveguides detector as well as modulator elements based on the electroabsorption effect. The ability to selectively grow Hg(1-x)Cd(x)Te on CdTe substrates by SiO2 masking has been demonstrated using the hydrogen-transport epitaxial technique. Detailed measurements have been made of mode propagation at 10.6 micrometers in n/n(+) CdTe planar waveguides formed by proton bombardment. Bragg-type acousto-optic modulators Rayleigh surface acoustic waves have been fabricated in such n/n(+) CdTe waveguides and a modulation efficiency for 10.6-micrometers light of 10% has been obtained at 27 MHz with about 0.5 W of acoustic power. Planar waveguides with propagation losses or = 1.5/cm (6.5 dB/cm) at 10.6-micrometers wavelength have been fabricated in the Pb(1-x)Sn(x)Te alloy system for eventual use in integrated 10.6-micrometers heterodyne receivers. See also report dated 31 Dec 1973, AD781102.